Corals biomineralization

Bone, shell, and coral are not, however, the only biominerals created by living organisms. The kidney and liver of animals, for example, often synthesize biominerals in the form of pathological stones (known as calculi) of varied composition (mostly of calcium oxalate, calcium phosphate, or... 

Because of its relatively long mean residence time, ocean water has a constant isotope composition. Corals are about l%c and foraminifera are about 4.5%o lighter than ocean water. Thus significant Mg isotope fractionations occur during biomineralization of carbonate secreting organisms which is larger than for Ca isotopes (see Section 2.11). 

AUemand, D., Tambutte, E., Girard, J. P., and Jaubert, J. (1988). Organic matrix synthesis in the scleratinian coral Stylophom pistiUata Role in biomineralization and potential target of the organotin tributyltin. J. Exp. Biol. 201, 2001-2009. 

Lowenstam and Weiner (1989, pp. 8-11, table 2.1) clearly show that carbonates dominate in biomineralization. They even occur in plants and fungi. The volume percent of limestone and marbles is well documented from the Precambrian to the present. Whether these rocks are inorganic precipitates or festooned with fossils, many of the living creatures had biomineralized with calcium carbonate, is usually clear. Indeed, some strata are composed entirely of calcium carbonate shells. We present examples of carbonate mineral deposition in cyanobacteria, corals, coccoliths, foraminifera, mollusks, echinoids, and the arthropods. 

Enzymes. An obvious additional factor in biomineralization is enzyme activity. Enzymes are involved in the movements of ions by membrane pumps, the synthesis of organic matrix and sclerotized skeletal material, photosynthesis of coral zooxanthellae, and reactions involving COj. The best studied of these is carbonic anhydrase which catalyses the reactions... 

Biomineralization occurs in the ocean (e.g., Ca in shells. Si in coral reefs) and on land in both plants (e.g.. Si in grasses) and animals (e.g., Ca in bone, Fe in ferritin, Fe in magnetic particles). Specific organic surfaces or matrices of protein and/or lipid allow living organisms to produce minerals of defined shape and composition, often in thermodynamically unstable states. 

Calcium carbonate is the most important biomineral, due to its presence in, e.g., mollusk shells, skeletons of foraminiferes, coccohthophores, or corals (see [6] for a recent review). 

For timescales spanning the last 50,000 years, radiocarbon dating is one of the most widely used dating techniques. It can be applied to organic material, biominerals (such as shell and coral), and in some cases to carbonate deposits and is therefore possible in a wide range of different environments. It is complementary to other techniques such as optically stimulated luminescence... 

GUI 95] GUILLEMIN G., PA TAT J.L. and MEUNIER A., Natural corals used as bone graft substitutes . Proceedings of 7 International Symposium on Biomineralization, Bulletin de ITnstitut Oceanographique, no. 14-3, p. 67-77,1995. 

The Earth s atmosphere contains about 0.03% by volume of CO2, and the equilibrium in Equation 10.2 means that rain falling through even unpolluted skies will be slightly acidic. CO2 is produced by respiration of plants and animals, but is used by plants in the photosynthesis of carbohydrates. The fossilization of plants in the Carboniferous Period (354-290 million years ago) was responsible for the production of coal. Marine organisms use forms of calcium carbonate (calcite and aragonite) in their exoskeletons. An example of the role of this biomineral in protection is shown in Figure 10.15. Some of these organisms live in coral reefs, but others swim about in the sea, and when they die their shells fall to the sea bed. 

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